To elucidate the extent of behavioral modification, presumably at the level of the brain, induced by the presence or absence of neonatal androgen or estrogen, a guantitative analysis of non-sexual behaviors of rats hormonally manipulated in infancy will be undertaken. Treatment groups will consist of: (1) females receiving various amounts of testosterone propionate; (2) females receiving testes implants; (3) males castrated on the day of birth; (4) males receiving gonadotropin antiserum neonatally and (5) females receiving various amounts of estradiol benzoate in infancy. All groups (gonadectomized at 50 days of age) if not sooner, i.e. males castrated at birth) will be tested for their responses in the open field and emergence test situations. The social and maternal behavior of all animals will be studied, and olfactory preferences will be examined. The principal objective of this experiment is to study behavior patterns that distinguish the male from the female. Once the "normal" patterns have been established for the control males and females, the responses of the experimental animals can be compared to the baseline of "normal" behavior shown by the controls. In this way one can determine how "masculine" the androgenized female has become, and how "feminine" the males castrated at birth and males receiving gonadotropin antiserum in infancy have become in the behavioral test situations.